The dedication of these individuals is noteworthy… What drives this persistence? Is it a deep-seated belief system that overrides rational analysis

It’s a lovely little combo of desperation and digging themselves into a hole. Most of the elements of sovereign citizens come from people who are not in good situations, as outlined by the canadian court’s very thorough opinion (which has already been linked twice in this thread, so I won’t bother it again). Once you’re in it, the same situation occurs that you can see with people in cults, mlm companies, or ponzi schemes. Maybe if you keep going, and pushing through the pain right now, you’ll get that mythical payoff. The alternative is to face the fact that you’ve likely ruined your life, rendering impossible whatever you hoped to achieve in the legal system in the first place.